Reciprocating plunger type pump



Sept. 12, 1967 Filed' June. 28, 1965 E. H. SCHANZLIN RECIPROCATING PLUNGER TYPE PUMP 2 Sheets-Sheet i;

in van/fir 5 /2655 15 150 %anzz'1z @M @mv %c flya United States Patent 3,340,818 RECIPROCATING PLUNGER TYPE PUMP Ernest H. Schanzlin, Olympia Fields, 111., assignor to Tuthill Pump Company, a corporation of Illinois Filed June 28, 1965, Ser. No. 467,636 3 Claims. (Cl. 103178) ABSTRACT OF THE DISCLOSURE The invention is concerned with a high capacity self priming reciprocating plunger type pump operating in the 1,800 rpm. range that is especially adapted for high pressure applications. The pump is of the single piston or plunger type in which the piston includes a check valve through which liquid passes on the piston power stroke that includes a special stopper or movement limiting device that avoids wear and permits an increased speed of operation. The pump includes a diaphragm device in communication with its intake passage that provides a continuing pumping action on the medium being pumped. The pump housing takes the form of separate sections that may be disposed at a variety of positions about the central axis of the pump to accommodate different insulation situations.

My invention relates to a reciprocating plunger type pump, and more particularly, to a high speed self-priming pump of this type which is adapted for high pressure use.

Reciprocating plunger type pumps ofthe single acting type heretofore have been limited to the 300 to 600 r.p.m. range while double acting pumps of thi type have been limited to about 1200 rpm; thus reciprocating plunger type pumps have heretofore operated at comparatively low capacities. In order to improve capacity they have been made fairly large in size, which not only limits their application, but further reduces their speed because of the inertia problems involved.

A principal object of my invention is to provide a high capacity reciprocating plunger type pump that operates in the 1,800 rpm. range, and that is especially adapted for high pressure applications.

Another object of the. application is to provide a reciprocating plunger type pump that is not only small in size but can have a useful life on the order of 25,000

hours serving in high pressure high speed type applica- I tions.

Other objects of the invention are to provide a reciprocating plunger type pump that is simplified and reliable in design, that is double acting and self-priming in operation, and that is economical of manufacture, efficient in use, and susceptible of a wide variety of applications.

Other objects, uses, and advantages will be obvious or become apparent from a consideration of the application drawings and the following detailed description.

In the drawings:

However, it is to be understood that the specific drawing illustrations provided are supplied primarily to comply with the requirements of 35 U.S.C. 112, and that the invention may have other embodiments which are intended to be covered by the appended claims.

General description Reference numeral 10 of FIGURES 1-3 generally indicates one embodiment of my invention which comprises a housing 12 defining a cylinder 14 in which is reciprocably mounted a piston or plunger 16 that is actuated through drive shaft 18 appropriately keyed or coupled to a prime mover of any appropriate type, which shaft '18 is in turn coupled to piston 16 by a suitable drive transmitting connection or coupling arrangement indicated at 20 in FIG- URE 2.

In accordance with my invention, the piston '16 is formed to define a valve chamber 22 having an inlet port 24 at the head end 26 of the piston and a plurality of outlet or discharge ports 28 (though only one is illustrated they are equally spaced about the axis of the piston, and if three in number, as in the present embodiment, they are spaced 120 degrees apart) formed in the shank 30 of the piston.

Received within the chamber 22 is a check valve member 32 that is applied in overlying relation to theinlet port 24, and a valve member stop device 34, the function of which, in accordance with this invention, is to limit the distance that valve member 32 may be displaced from the position shown in FIGURE 1.

The stopper device 34 comprises a pedestal or stem 36 having a planar upper end surface 38 and defining atits base 40 a spring seat 42 for a compression spring 44 which is interposed between the stopper device 34 and valve member 32 to bias the valve member 32 against its valve seat 46. Valve member 32 is formed to define spring seat 48 and stem portion 50 having a planar surface 52 adaptedto be engaged by the surface 38 -of stopper device 34.

The surfaces 38 and. 52 as well as valve seat 46 are planar in configuration and lie in planes which extend transversely of or perpendicular to the'direction of movement of the piston 16.

The housing 12 defines an inlet port 60 leadin'g'to an accumulator chamber 62 whichis partially defined by a diaphragm device 64 positioned across housing recess 66 (that is vented by port 67), and which is biased outwardly of chamber 62 and inwardly of recess 66 by compression FIGURE 1 is a sectional view, partially in elevation,

illustrating the internal details of a pump arranged in accordance with my invention;

FIGURE 2 is a fragmental cross-sectional view substantially along line 2-2 of FIGURE 1, illustrating the drive arrangement of the pump;

FIGURE 3 is a top plan view of the pump shown in FIGURE 1;

FIGURES 4, 5, 6, and 7 are small scale diagrammatic views illustrating various ways in which the top and intermediate or center sections of this pump may be assembled with respect to each other;

FIGURE 8 is a view similar to that of FIGURE 1 illustrating a modified form of the invention; and FIGURE 9 is a side elevational view of the pump shown in FIGURE 8, with parts being shown in section.

spring 68.

Chamber 62 communicates with a check valve chamber" 70 through a plurality of spaced passages or conduits 72, flow through'which is controlled by a check valve 74.-

Check valve 74 includes a planar valve member 76 cooperating with a planar valve seat 78 to close off flow through passages 72 under the action of a compression spring 80 acting on its stem 82. i In the arrangement shown in FIGURES 1-7, the cylinder 14 is defined by a plastic sleeve which is formed with a plurality of equally spaced ports 92 leading to an annular recess 94 formed in the housing and defining a liquid pooling area 96. Housing 12 is formed to definean outlet port 98 with which the pooling area '96 communicates. The piston 16 at its'crank end 100 is connected to the coupling device 20 in the manner indicated in FIG- URE 2.

change of direction point between its return and pump intake or retraction strokes. As the piston moves downwardly of the showing of FIGURE 1 with respect to cylinder 14, valve 74 is lifted (by suction) off its seat 78 and liquid is drawn into check valve chamber 70 and thence into cylinder 14 as piston 16 continues on its intake stroke. Valve member 32 remains in engagement with its valve seat 46 under the action of spring 44 during this direction of movement of the piston and by the vacuum generated during the piston retraction, and also under the action of the liquid contained within the annular pump chamber 103 (that is defined by the piston and its cylinder) which is being pushed outwardly of the cylinder through ports 92 into pooling chamber 96 and thence outwardly of the pump outlet 98.

When piston 16 changes its direction at the end of its intake or retraction stroke, spring 80 acting on valve member 76 closes off passages 72, and the liquid under compression within cylinder 14 and chamber 70 overcomes the biasing action of spring 44 and the liquid pressure in the piston valve chamber 22 to move valve member 32 off its seat and permit liquid flow through the piston inlet 24 and thence outwardly of chamber 22 through ports 28 into chamber 103.

The stopper device during the functioning of pump stops and holds valve member 32 at a predetermined position and at a predetermined spacing from valve seat 46, and as piston 16 reaches the end of its stroke in the direction of check valve 74, compression spring 44 moves valve member 32 back into position against valve seat 46, whereupon the cycle repeats itself.

The stopper device 34 serves the important function of maintaining the valve member 32 oriented in parallel relation with valve seat 46, and it is preferred that the stopper device 34 be proportioned to limit movement of valve member 32 away from its seat to a distance in the range of approximately to of an inch. The position maintaining function of device 34 avoids cooking of the valve member 32 under the action of liquid flow by same, with consequent wear on the valve member 32 when it is returned to its valve seat. The spacing range indicated provides for a relatively small movement between the open and closed positions of the valve member 32, and consequently, valve 46 becomes effective to either open or close the passage it cooperates with at a faster rate. The over-all result is that the stopper device 34 considerably increases the useful life and capacity of pump 10 over comparable devices.

During the intake stroke of piston 16, that is, when piston 16 is moving downwardly of FIGURE 1, the medium being pumped, such as water, is being drawn through valve 74 from chamber 62 and the source of liquid to which chamber 62 is connected. Under the suction action thereby being provided by piston 16, atmospheric pressure acting on diaphragm device 64 compresses its spring 68 and tends to deflect or distend into the chamber 62.

On change of direction of the movement of piston 16, the flow from the chamber 62 through passages 72 stops, spring 68 immediately becomes effective to press the diaphragm device into recess 66 and thus outwardly of the chamber 62, thereby providing a suction action on the medium being pumped which continues movement of the liquid in pump inlet 60 in the direction of the chamber 62. This thus permits continuation of the flow of the liquid into pump 10 during the return stroke of piston 16, which avoids a characteristic stop and go flow action of liquid into pumps of this type due to the normal single acting nature of reciprocating piston type pumps. Thus, the diaphragm device 64 acts as an auxilliary pumping device to keep the inlet flow in motion during the return stroke of the piston. It has been found that without this the pump vibrates excessively at higher speeds and conduiting connected to the pump inlet jumps excessively from the inertia of the liquid alternately stopping and starting.

Another significant aspect of the pump lies in the minimum clearance volume that is present at the head end of the piston at the end of its return or extended stroke (the position of FIGURE 1), as this tends to improve priming in view of the fact that there is less air to be acted on when the pump is being started. This arrangement is an important factor in making pump 10 self-priming.

Tests have shown that specific embodiments of pump 10 operate efficiently at 1,800 r.p.m., as distinguished from the conventional 300 to 1200 r.p.m. for pumps of this general type. The few and simple moving parts of pump 10 plus the special function of stopper device 34 provide a pump arrangement that tests have shown to have a useful life on the order of 1,500 hours under high pressure operating conditions and which is capable of a useful life on the order of 25,000 hours.

The pump of FIGURES 8 and 9 is generally similar to pump 10 except for a modified piston valve stopper device 122 and the use of the crank shaft drive arrangement 124 for actuating the piston. In the showing of FIGURES 8 and 9, parts similar to the showing of FIGURES l-7 are indicated by like reference numerals with the suffix A, and with regard to the stopper device 122 it will be seen that valve member 32A is formed with an extended stem portion 50A having a planar annular end surface 52A which engages the surface 125 of valve chamber 22A. Surfaces 52A and 125 are planar in configuration and are disposed in planes that are parallel to the plane of valve seat 46A, and compression spring 44A operates between the surface 125 and spring seat 48A to bias valve member 32A against its valve seat 46A.

The crank shaft coupling arrangement 124 comprises a crank arm 128 eccentrically journalled on shaft 130, with the shaft 130 being driven in any suitable manner. Crank arm 128 in accordance with this embodiment of the invention has a universal ball and socket joint type coupling connection with piston 16A where indicated at 132, and it is preferable that this connection be positioned as closely as possible to the mid point in the length of piston 16A.

The pump 120 has operating characteristics similar to those of pump 10 except that it is designed to operate under higher pressure conditions.

Specific description Referring again to the embodiment of FIGURES 1-7, the housing 12 is preferably arranged in three sections, that is, a bottom or drive section 140, a center section 142 in which the piston 16 operates, and a top section 144 in which check valve device 74 and diaphragm device 64 are mounted.

The top section 144 is provided with a cover or cap 146 which is formed to define the housing recess 66 and it also secures the diaphragm device 64 in place.

The diaphragm device 64 comprises a sheet 150 of resiliently flexible material, such as a suitable metallic or non-metallic substance (or a suitable combination or lamination of the two), which is preferably formed to define a seat 152 for spring plate 154 against which one end of compression spring 68 bears. The other end of compression spring 68 bears against a suitable annular seat 156 formed in housing section 144 about chamber 62.

The cover 146, diaphragm forming sheet 150, and the housing sections are formed to receive the four assembly bolts 160 which secure the pump housing components together.

The bolts 160 pass through the cap 146, sheet 150, and the sections 144 and 142 for engagement in tapped holes appropriately formed in housing section 140, and in accordance with this invention the formation of the bolt holes through sections 144 and 142 is arranged so that sections 142 and 144 may be alternately positioned with respect to each other in one of the positions suggested by FIGURES 4-7. Alternately, the section 142 may be disposed in one of four positions 90 degrees apart about the longitudinal axis of piston 16.

Consequently, the pump is readily adapted for sixteen different types of porting arrangements or connections by appropriately positioning the housing sections 142 and 144 with respect to each other and to the bottom section 140. The figuration of the housing sections is such that the pump operates precisely the same for any orientation position selected.

As indicated in FIGURE 1, the diaphragm forming sheet 150 is secured in place by having its edge or border portion 162 clamped against the housing section 144 when bolts 160 are tightened into place.

The check valve device 74 comprises the valve member 76 and its stem 82 which is slidably mounted in housing wall 164 through which passages 72 extend. Passages 72 may be of any suitable number and preferably are spaaced equidistantly apart about stem 82.

Compression spring 80 seats between a spring seat 170 formed on housing wall 164 and a shoulder or ridge 172 formed on the end of stem 82.

In the area of valve seat 78, the housing section 144 is formed with an annular recess 176 that receives O-ring seal 178 and the proportioning of these components is such that the valve member 76 is placed in sealing engagement with the O-ring seal 176 when it is seated against its valve seat 78.

Check valve chamber 70 is defined by recess 180 formed in housing section 144.

Housing section 142 is formed with cylindrical bore 190 that is proportioned to receive sleeve 90, and preferably the portioning of parts involved is that sleeve 90 readily slides into the bore 190, although its exterior configuration should substantially complement the internal diameter of bore 190.

The internal configuration of sleeve 90 is preferably of the stepped diameter configuration indicated thereby defining the cylinder 14 at one end thereof in which the piston head 26 operates and a piston guiding portion 194 that aids in guiding the longitudinal reciprocating movement of the piston.

Sleeve 90 is preferably formed from a suitable graphitic phenol-formaldehyde product, an example of which is Durez 750 made by Durez Plastics Division, Hooker Chemical Corp.

Suitable seals 196 are carried by the piston for cooperation with the cylinder and the housing section 142 is counterbored about bore 190 to receive appropriate O-ring seal 198.

In the specific embodiment of FIGURES 1-7 the piston inlet 24 is defined by an annular member 200 that is screwed into place within the piston 16 in a threaded counterbore 202. The valve chamber 22 of piston 16 is defined by the annular member 200 and enlargement 204 of piston bore 205, the enlargement defining a seat 206 on which the stopper member 34 is mounted. Seat Y 206 should lie in a plane parallel to the plane of valve seat 46, and the contacting surfaces of stopper member 34 and seat 206 should have complementary configurations, as for instance planar (as illustrated) or conical.

Valve member 32 and stopper device pedestal 36 are preferably formed from a substance equivalent to the acetal resin product sold by Du Pont under the trademark Delrin.

The lower housing section 140 is preferably formed to define a shaft receiving chamber 210 in which are mounted appropriate bearing devices 212 that journal shaft 18. Shaft 18 at its end 214 is formed to define an eccentrically disposed stud portion 216 on which is journalled a bearing assembly 218 of any suitable type that operatively engages within a slot 220 formed in the crank end 30 of piston 16. Piston 16 extends through suitable bore 222 formed in the housing section 140, which is counterbored at 224 to receive U-shaped seal 226 (defining upstanding lips 227 and 229) and is further recessed as at 230 to receive the end of the cylinder defining sleeve 90, as indicated in FIGURE 1.

As is also indicated in FIGURE 1, the end portion 194 of the sleeve is formed with a passage 240 which extends between one ort 92 and the end portion 242 of the sleeve. This disposes the end 244 of passage 240 adjacent the seal 226, and this provides a circulation of the liquid being pumped to positively engage lip 229 of seal 226 into sealing engagement with the piston and circulate liquid between the piston and sleeve portion 194, the seal 226, passage 240, and port 92, which has been found to provide a beneficial cooling action on the contacting surfaces of the piston and sleeve in the area of the sleeve portion 194.

As indicated in FIGURE 1, the housing section 142 is formed with an annular flange portion 250 that is adapted to seat within the recessed portion 230, the latter also being proportioned to receive a suitable O-ring seal 252.

As indicated in FIGURE 2, the shaft receiving chamber 210 of housing section 140 is closed in the area of coupling device 20 by a suitable cap 254 of any appropriate character.

Turning now to the embodiment of FIGURES 8 and 9, the housing 12A of pump comprises a bottom section 260, a center section 262, and a top section 264 that are related for assembly purposes in the same manner as suggested by FIGURES 4-7.

The top housing section 264 and its assembled components are substantially identical to those described in connection with the embodiments of FIGURES 1-7, as indicated by corresponding reference numerals, although the proportioning may be somewhat different.

The housing section 262 and its sleeve 90A are likewise similar to the corresponding housing section and sleeve of the embodiment of FIGURE 1, as indicated by the corresponding reference numerals.

With regard to the piston 16A, the inlet to chamber 22A is defined by a plurality (for instance, four) of inlet passages 24A formed in disc member 200A that is screw threaded into the piston. Chamber 22A itself in this embodiment of the invention contains a spacer member 270 received within the enlargement 272 of the piston bore 273 and having itsend portion 274 engaging bearing member 276 which journals the bearing bushing 278 of crank arm 128.

The spacer 270 defines a transversely extending wall structure 280 on which the planar stop surface is formed.

The spacer 270 at its end portion 283 engages disc member 200A, and is formed with ports 287 which communicate with a pooling area 285 defined by annular groove 282 formed in piston 16A. An appropriate seal 284 is applied between the spacer 270 and sleeve 90A for appropriate sealing purposes.

As previously indicated, the connection between crank arm 128 and piston 16A should be located at as close as practically possible to the midportion of the length of the piston 16A. This will achieve a desired balance between the tilting forces that act on the piston on its forward and return strokes.

As indicated in FIGURE 8, the crank arm 128 extends upwardly through bore 273 of the piston, and the crank arm 128 is provided with an appropriate grease fitting 292 and connection passageways 294 and 296 that lead up to the ball joint 278 for appropriate lubricating purposes. I

As indicated in FIGURE 9, the housing section 260 is formed with a shaft journalling chamber 210A in which are mounted appropriate bearing assemblies 212A for journalling the shaft 130. A suitable needle bearing type assembly 298 maybe interposed between the crank arm 128 and an eccentric portion 300 of shaft 130 for purposes of journalling the crank arm 128 on shaft 130. Grease seals 302 are provided to seal grease packed in assembly 298 for the life of the hearing.

The pump 120 in operation functions substantially the same as pump 10.

It will therefore be seen that I have provided a reciprocating plunger type pump arrangement which normally operates at relatively high speeds with corresponding increased capacity over conventional arrangements. Also, the structural features that permit the high speed operation contribute to the extended useful life of this pump arrangement since excessive wear of critical parts is eliminated and the simplification involved reduces the prospect of mechanical difiiculties developing.

My pump arrangement, by virtue of the diaphragm arrangements 64 and 64A, is double acting in nature, and the minimum clearance volume at the end of the piston as it completes its return stroke permits the pump to be selfpriming in nature.

The multiple position possibilities of the pump housing segments readily adapt the pump for application to a wide variety of installation arrangements, and the over-all simplicity of the invention insure reduced manufacturing and assembly costs.

The foregoing description and the drawings are given merely to explain and illustrate my invention and the invention is not to be limited thereto, except insofar as the appended claims are so limited, since those skilled in the art who have my disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.

I claim:

1. A reciprocating plunger pump comprising:

a housing defining a cylinder,

a piston reciprocably mounted in said cylinder and defining a head end at one end thereof and a crank end at the other end thereof,

drive means coupled with said piston crank end for reciprocating same,

said piston being formed to define a valve chamber,

said piston head end being ported to define an inlet to said valve chamber,

check valve means cooperating with said piston head inlet to preclude liquid flow from said valve chamber on movement of said piston in the direction of its said crank end,

said check valve means comprising:

a valve seat formed in said piston in circumambient relation about said piston head inlet and lying in a plane extending transversely of the path of reciprocating movement of said piston,

a check valve member received in said valve chamber and positioned in alignment with said valve seat,

and means for resiliently biasing said valve member into engagement with said valve seat,

said piston being formed to define outlet port means in communication with said valve chamber,

said housing being formed to define inlet and outlet conduit means in communication with said piston inlet port and said piston outlet port means, respectively,

said housing inlet conduit means including check valve means for precluding fluid flow therethrough upstream thereof on movement of said piston in the direction of its head,

and stop means carried by said piston and cooperating with said piston valve member to limit unseating movement of said piston valve member in opposition to said biasing means thereof,

said housing check valve means comprising:

a planar valve seat and a planar valve member cooperating in check valve relation with same and being disposed in planes that extend transversely of said path of said piston,

means for resiliently biasing said housing check valve means valve member against its said seat,

said housing check valve means valve member being positioned to be disposed in juxtaposition to said piston head end at the change of direction position of said piston when at the head end of said cylinder, whereby a minimum clearance volume is provided at said piston head when said piston is in said change of direction position thereby providing minimum fluid to be acted on when the pump is to be started,

said housing comprising:

a center section including said cylinder,

said center section defining said outlet conduit means,

a head end section removably secured to the head end of said center section,

said head end section defining said inlet conduit means and carrying said housing check valve means and separating from said center section at the head end of said cylinder,

and a crank end section secured to the crank end of said center section,

said crank end section carrying said drive means and separating from said center section at the crank end of said cylinder,

said head end and said center sections of said housing being formed to provide multiple position assembly of same with respect to each other and said crank end section about the central axis of said piston, in full pump operating relation.

2. The pump set forth in claim 1 wherein:

said cylinder is defined by a liner member slip fitted within said housing center section,

said liner member being formed with one or more ports in communication with said housing outlet conduit means,

and including seal means mounted in said housing crank end section and engaging said piston adjacent said crank end thereof in the assembled relation of said housing sections,

and wherein said liner member is in juxtaposition with said seal means in said assembled relation of said housing sections,

said liner member at one of its said ports being formed with a conduit leading between said one port and said seal means for providing a circulation of the fluid being pumped along said piston crank end and for biasing said seal means into fluid tight relation with said piston on operation of said pump.

3. The pump set forth in claim 1 wherein said drive means comprises:

a crank member,

eccentric drive means for actuating said crank member,

and a universal type joint coupling device coupling said crank member to said piston for eifecting reciprocation of said piston,

said coupling device being disposed adjacent half way between said ends of said piston.

References Cited UNITED STATES PATENTS 1,128,089 2/1915 Astrom 103216 2,139,972 12/1938 Rokkjar 103182 2,612,837 10/1952 Midgette 103--182 2,811,929 11/1957 Rupp 103-223 3,089,430 5/1963 Shafer et a1. 103228 3,100,449 8/1963 Dahl 103l78 3,259,076 7/1966 Halberg et a1. 103215 FOREIGN PATENTS 1,371,922 8/ 1964 France.

918,042 9/1954 Germany.

DONLEY I. STOCKING, Primary Examiner.

WILLIAM L. FREEH, Alssistant Examiner. 

1. A RECIPROCATING PLUNGER PUMP COMPRISING: A HOUSING DEFINING A CYLINDER, A PISTON RECIPROCABLY MOUNTED IN SAID CYLINDER AND DEFINING A HEAD END AT ONE END THEREOF AND A CRANK END AT THE OTHER END THEREOF, DRIVE MEANS COUPLED WITH SAID PISTON CRANK END FOR RECIPROCATING SAME, SAID PISTON BEING FORMED TO DEFINE A VALVE CHAMBER, SAID PISTON HEAD END BEING PORTED TO DEFINE AN INLET TO SAID VALVE CHAMBER, CHECK VALVE MEANS COOPERATING WITH SAID PISTON HEAD INLET TO PRECLUDE LIQUID FLOW SAID VALVE CHAMBER ON MOVEMENT OF SAID PISTON IN THE DIRECTION OF ITS SAID CRANK END, SAID CHECK VALVE MEANS COMPRISING: A VALVE SEAT FORMED IN SAID PISTON IN CIRCUMAMBIENT RELATION ABOUT SAID PISTON HEAD INLET AND LYING IN A PLANE EXTENDING TRANSVERSELY OF THE PATH OF RECIPROCATING MOVEMENT OF SAID PISTON, A CHECK VALVE MEMBER RECEIVED IN SAID VALVE CHAMBER AND POSITIONED IN ALIGNMENT WITH SAID VALVE SEAT, AND MEANS FOR RESILIENTLY BIASING SAID VALVE MEMBER IN ENGAGEMENT WITH SAID VALVE SEAT, SAID PISTON BEING FORMED TO DEFINE OUTLET PORT MEANS IN COMMUNICATION WITH SAID VALVE CHAMBER, SAID HOUSING BEING FORMED TO DEFINE INLET END OUTLET CONDUIT MEANS IN COMMUNICATION WITH SAID PISTON INLET PORT AND SAID PISTON OUTLET PORT MEANS, RESPECTIVELY, SAID HOUSING INLET CONDUIT MEANS INCLUDING CHECK VALVE MEANS FOR PRECLUDING FLUID FLOW THERETHROUGH UPSTREAM THEREOF ON MOVEMENT OF SAID PISTON IN THE DIRECTION OF ITS HEAD, AND STOP MEANS CARRIED BY SAID PISTON AND COOPERATING WITH SAID PISTON VALVE MEMBER TO LIMIT UNSEATING MOVEMENT OF SAID PISTON VALVE MEMBER IN OPPOSITION TO SAID BIASING MEANS THEREOF, SAID HOUSING CHECK VALVE MEANS COMPRISING: A PLANAR VALVE SEAT AND A PLANAR VALVE MEMBER COOPERATING IN CHECK VALVE RELATION WITH SAME AND BEING DISPOSED IN PLANES THAT EXTEND TRANSVERSELY OF SAID PATH OF SAID PISTON, MEANS FOR RESILIENTLY BIASING SAID HOUSING CHECK VALVE MEANS VALVE MEMBER AGAINST ITS SAID SEAT, SAID HOUSING CHECK VALVE MEANS VALVE MEMBER BEING POSITIONED TO BE DISPOSED IN JUXAPOSITION TO SAID PISTON HEAD END AT THE CHANGE OF DIRECTION POSITION OF SAID PISTON WHEN AT THE HEAD END OF SAID CYLINDER, WHEREBY A MINIMUM CLEARANCE VOLUME IS PROVIDED AT SAID PISTON HEAD WHEN SAID PISTON IS IN SAID CHANGE OF DIRECTION POSITION THEREBY PROVIDING MINIMUM FLUID TO BE ACTED ON WHEN THE PUMP IS TO BE STARTED, SAID HOUSING COMPRISING: A CENTER SECTION INCLUDING SAID CYLINDER, SAID CENTER SECTION DEFINING SAID OUTLET CONDUIT MEANS, A HEAD END SECTION REMOVABLY SECURED TO THE HEAD END OF SAID CENTER SECTION, SAID HEAD END SECTION DEFINING SAID INLET CONDUIT MEANS AND CARRYING SAID HOUSING CHECK VALVE MEANS AND SEPARATING FROM SAID CENTER SECTION AT THE HEAD END OF SAID CYLINDER, AND A CRANK END SECTION SECURED TO THE CRANK END OF SAID CENTER SECTION, SAID CRANK END SECTION CARRYING SAID DRIVE MEANS AND SEPARATING FROM SAID CENTER SECTION AT THE CRANK END OF SAID CYLINDER, SAID HEAD END AND SAID CENTER SECTIONS OF SAID HOUSING BEING FORMED TO PROVIDE MULTIPLE POSITION ASSEMBLY OF SAME WITH RESPECT TO EACH OTHER AND SAID CRANK END SECTION ABOUT THE CENTRAL AXIS OF SAID PISTON, IN FULL PUMP OPERATING RELATION. 